* NXP LPC1850 Clock Generation Unit (CGU)
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The CGU generates multiple independent clocks for the core and the
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peripheral blocks of the LPC18xx. Each independent clock is called
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a base clock and itself is one of the inputs to the two Clock
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Control Units (CCUs) which control the branch clocks to the
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individual peripherals.
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The CGU selects the inputs to the clock generators from multiple
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clock sources, controls the clock generation, and routes the outputs
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of the clock generators through the clock source bus to the output
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stages. Each output stage provides an independent clock source and
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corresponds to one of the base clocks for the LPC18xx.
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- Above text taken from NXP LPC1850 User Manual.
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This binding uses the common clock binding:
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Documentation/devicetree/bindings/clock/clock-bindings.txt
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Required properties:
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- compatible:
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Should be "nxp,lpc1850-cgu"
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- reg:
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Shall define the base and range of the address space
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containing clock control registers
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- #clock-cells:
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Shall have value <1>. The permitted clock-specifier values
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are the base clock numbers defined below.
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- clocks:
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Shall contain a list of phandles for the external input
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sources to the CGU. The list shall be in the following
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order: xtal, 32khz, enet_rx_clk, enet_tx_clk, gp_clkin.
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- clock-indices:
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Shall be an ordered list of numbers defining the base clock
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number provided by the CGU.
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- clock-output-names:
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Shall be an ordered list of strings defining the names of
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the clocks provided by the CGU.
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Which base clocks that are available on the CGU depends on the
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specific LPC part. Base clocks are numbered from 0 to 27.
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Number: Name: Description:
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0 BASE_SAFE_CLK Base safe clock (always on) for WWDT
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1 BASE_USB0_CLK Base clock for USB0
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2 BASE_PERIPH_CLK Base clock for Cortex-M0SUB subsystem,
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SPI, and SGPIO
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3 BASE_USB1_CLK Base clock for USB1
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4 BASE_CPU_CLK System base clock for ARM Cortex-M core
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and APB peripheral blocks #0 and #2
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5 BASE_SPIFI_CLK Base clock for SPIFI
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6 BASE_SPI_CLK Base clock for SPI
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7 BASE_PHY_RX_CLK Base clock for Ethernet PHY Receive clock
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8 BASE_PHY_TX_CLK Base clock for Ethernet PHY Transmit clock
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9 BASE_APB1_CLK Base clock for APB peripheral block # 1
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10 BASE_APB3_CLK Base clock for APB peripheral block # 3
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11 BASE_LCD_CLK Base clock for LCD
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12 BASE_ADCHS_CLK Base clock for ADCHS
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13 BASE_SDIO_CLK Base clock for SD/MMC
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14 BASE_SSP0_CLK Base clock for SSP0
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15 BASE_SSP1_CLK Base clock for SSP1
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16 BASE_UART0_CLK Base clock for UART0
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17 BASE_UART1_CLK Base clock for UART1
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18 BASE_UART2_CLK Base clock for UART2
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19 BASE_UART3_CLK Base clock for UART3
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20 BASE_OUT_CLK Base clock for CLKOUT pin
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24-21 - Reserved
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25 BASE_AUDIO_CLK Base clock for audio system (I2S)
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26 BASE_CGU_OUT0_CLK Base clock for CGU_OUT0 clock output
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27 BASE_CGU_OUT1_CLK Base clock for CGU_OUT1 clock output
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BASE_PERIPH_CLK and BASE_SPI_CLK is only available on LPC43xx.
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BASE_ADCHS_CLK is only available on LPC4370.
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Example board file:
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/ {
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clocks {
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xtal: xtal {
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compatible = "fixed-clock";
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#clock-cells = <0>;
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clock-frequency = <12000000>;
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};
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xtal32: xtal32 {
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compatible = "fixed-clock";
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#clock-cells = <0>;
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clock-frequency = <32768>;
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};
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enet_rx_clk: enet_rx_clk {
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compatible = "fixed-clock";
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#clock-cells = <0>;
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clock-frequency = <0>;
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clock-output-names = "enet_rx_clk";
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};
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enet_tx_clk: enet_tx_clk {
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compatible = "fixed-clock";
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#clock-cells = <0>;
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clock-frequency = <0>;
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clock-output-names = "enet_tx_clk";
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};
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gp_clkin: gp_clkin {
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compatible = "fixed-clock";
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#clock-cells = <0>;
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clock-frequency = <0>;
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clock-output-names = "gp_clkin";
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};
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};
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soc {
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cgu: clock-controller@40050000 {
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compatible = "nxp,lpc1850-cgu";
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reg = <0x40050000 0x1000>;
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#clock-cells = <1>;
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clocks = <&xtal>, <&creg_clk 1>, <&enet_rx_clk>, <&enet_tx_clk>, <&gp_clkin>;
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};
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/* A CGU and CCU clock consumer */
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lcdc: lcdc@40008000 {
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...
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clocks = <&cgu BASE_LCD_CLK>, <&ccu1 CLK_CPU_LCD>;
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clock-names = "clcdclk", "apb_pclk";
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...
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};
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};
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};
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